Designing an ultrasensitive immunosensor based on MWCNT/ZnS@CdS nanocomposite as an electrode surface modifier for detection of CEA biomarker.

The use of biosensor techniques in the detection of the analytes at trace amounts is of great interest. In particular, electrochemical immunosensors offer an accurate and efficient analytical method for the measurement of biomarkers. Carcinoembryonic antigen (CEA) is a biomarker commonly used in the monitoring of individuals with colon cancer. In this study, the surface of a glassy carbon electrode (GCE) was modified with a nanocomposite of multi-walled carbon nanotubes (MWCNTs) and ZnS@CdS core-shell quantum dots (QDs). Due to the highly desirable physicochemical properties of these nanomaterials, the immunosensor designed in this study demonstrated the ability to detect CEA in a wide linear range from 0.0005 to 2.5 ng/mL, with a limit of detection (LOD) of 0.11 pg/mL. The electrode surface materials also offered excellent stability and properties. Considering the results of the immunosensor in CEA assay, it can be inferred that this new biosensor is a promising device for accurate CEA detection.